Questions Regarding Siamesed Intake Ports (9 Port Head)

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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by MadBill » Sat May 20, 2017 9:02 am

I see little icons boxes with a green page outline and the word IMAGE. Usually such open at a click, but not these ones.. :(
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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by enigma57 » Sun May 21, 2017 6:01 am

Sorry the photos on my thread are not visible to you, Bill. I can forward them by E-mail if you wish. PM sent.

Best regards,

Harry

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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by MadBill » Sun May 21, 2017 9:10 am

Thanks Harry.
Wilco.
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Post by 4sfed » Sun May 21, 2017 10:22 am

MadBill wrote:Thanks Harry.
Wilco.
Bill,

Would you try posting the photos for the rest of us?

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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by MadBill » Sun May 21, 2017 10:35 am

10-4
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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by enigma57 » Mon May 22, 2017 12:45 am

Bill, I will be e-mailing you the files shortly. Asked my wife to make images smaller and will see if I can post them here.

This is when I began modifying the intake that will form outboard half of 2-piece intake. Triangular shaped aluminum filler plugs 2" long are hand fitted (slight interference fit) and will be welded in to close off the space between ports as they diverge towards original DCOE mounting flange.

There are also 3 pieces 1/2" thick that will blank off what were originally the headport openings.

Once that is done, I have 3 carb mounting flanges for 42 DCNF that will be welded to top of runners to convert from DCOE sidedraught to DCNF downdraught.

That's what I am doing in photos here to ready intake priour to sending it to Nick for welding and machining. Ably assisted by Holmes of course (we have 2 new kittens, Holmes and Watson)......
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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by enigma57 » Mon May 22, 2017 1:00 am

1 more photo of initial fit up priour to sending intake to Nick for welding and machining......
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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by enigma57 » Mon May 22, 2017 1:46 am

These are photos Nick has taken as welding and machining progress. Original headport openings are now blanked off. Spaces between runners have been filled and machined in preparation of welding carb mounting flanges in place.

Intake is now ready for last round of welding (to weld the DCNF downdraught carb mounting flanges in place). Next step will be to bore down through throttle bore holes and open them into port rooves below......
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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by enigma57 » Mon May 22, 2017 3:49 am

Well, those are the initial modifications to convert this half of what will now be a 2-piece intake...... From mounting 3 Weber DCOE sidedraught carburettors...... To mounting 3 Weber DCNF downdraught carburettors.

The inboard intake will remain unmodified......

Image

And the modified intake will be attached outboard at the DCOE carb mounting flange so as to form a 2-piece intake. This arrangement results in longer runners than that provided by the single DCOE sidedraught intake, but also clears the master cylinder and steering column in my '57 Chevy. In theory, the 2-piece design would also allow me to place a spacer between the inboard and outboard intake halves to further increase runner length and adjust tuned length a bit. However, I doubt there will be room for that in this instance.

Once I have intake back from Nick, I must add a small balance tube connecting all 3 mini-plenums (to smooth idle a bit, will not be large enough to form a common plenum). Will also work out a way to heat floors of all three mini-plenums with engine coolant. Work up throttle linkage and fuel log. Rebuild and rejet 3 of the 42 DCNF carbs I have here. (These particular carbs are original to a Maserati Quattroporte.)

Image

Best regards,

Harry
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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by Truckedup » Mon May 22, 2017 8:39 am

Harry, the head work used and retaining the Siamese ports may seem out of place to V8 guys..But a properly reworked stock head can support 1.5 HP per cubic...However, I believe it would be very lumpy for street use...
I was a actively involved in the Inliners club for many years...There was talk of Chevy 6's blowing off well modified V8's on the street..I personally never saw any Chevy 6 powered street cars capable of this performance...I think it might be like flat head Ford V8's where the typical street build makes 160 HP but there's always the talk of the few with time and money to make way more power ....I believe a nicely done up 292 with decent street manners might make near 300 HP if reasonable low end power is required...
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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by enigma57 » Tue May 23, 2017 4:27 am

:D Hi, Tony! Yes, that is my goal. Around 1.0 to 1.2 HP per cu. in. displacement. Decent street manners with lots of torque and a fairly flat power curve. Just having fun with this. No intention of competing with the V-8 crowd, although I remember a fellow back in 1960 who was in a couple of my classes. He had a Confederate gray '49 Plymouth sedan with a 'built' flathead 6. Shaved head, 3/4 race cam, split exhaust, dual carburettors, sweet pipes. Man, would that thing go!

Hoping to keep the stick shift tranny in my '57 (not fond of slush boxes). Right now, left knee is giving me a lot of pain, though. Having to use 2 canes to get around. Bottom line...... Transmission choice will depend upon how well the knee is doing when its time to make that decision. If I have to go with an automatic, I'll have to use a milder cam, correspondingly lower static compression ratio and smaller chokes in carbs than I have in mind at present, so power would be around 1.0 HP per cu. in. displacement at best if it works out that way.

Best regards,

Harry

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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by Truckedup » Tue May 23, 2017 6:24 am

I don't know if it's been mentioned ,but Sissel is a well known for Chevy 6 performance..... http://www.sissellautomotive.com/
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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by enigma57 » Wed May 24, 2017 3:09 am

Thanks, Tony! Yes, looking at Sissel, 12bolt.com, Mercruiser, AussieSpeed and others for engine parts and lump port sources. If I had the bucks, I would have gone for the 12-port Sissel aluminum head so I could make a true IR intake for this engine. Even considered building an OHC Pontiac Sprint engine at one point. But decided that for what I am doing here, a reworked 9-port iron head with lump ports on the 292 Chevy tall deck block would be the way to go....... And within my budget. Also easier to find parts for than the Pontiac cammer.

Surprising how many performance parts were/are made in Brazil for these Chevy inline 6 engines. The intake manifolds I am using ('Engine' brand) to make this DCNF carburettor conversion were made there. Very good quality castings. I looked the manufacturer up, but their website is kaput so don't know if they are still in business.

Best regards,

Harry

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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by enigma57 » Tue Jul 25, 2017 4:31 am

:D Update......

Some pics of the modified outboard half of intake. Still have much to do......

Image

Image

Image

After welding, Nick shot peened the intake to give it an 'as cast' look and make it harder to tell the intake has been welded. Then he did a skim cut on gasket sealing surfaces to eliminate any warpage from the heat of welding. I'm very happy with the outcome......

Image

Image

Will let you know how the intake is progressing once I have more to report. Just now, I am scrounging up parts to adapt larger '59 - '64 Chevy drum brakes to my '57. No modern store bought disc brake conversions here.

Thanks for your input and best regards to all,

Harry

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Re: Questions Regarding Siamesed Intake Ports (9 Port Head)

Post by roc » Tue Jul 25, 2017 1:29 pm

enigma57 wrote::D Update......

Some pics of the modified outboard half of intake. Still have much to do......

Image

Image

Image

After welding, Nick shot peened the intake to give it an 'as cast' look and make it harder to tell the intake has been welded. Then he did a skim cut on gasket sealing surfaces to eliminate any warpage from the heat of welding. I'm very happy with the outcome......

Image

Image

Will let you know how the intake is progressing once I have more to report. Just now, I am scrounging up parts to adapt larger '59 - '64 Chevy drum brakes to my '57. No modern store bought disc brake conversions here.

Thanks for your input and best regards to all,

Harry
Supreme craftsmanship Harry! I'm following this thread very closely, love inline sixes.
PS.: PM me if you need to get in touch with the manifold supplier (Engine), we were in touch about 10 years ago.

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